A verification code is a public full-automatic program for distinguishing whether an access requester is a computer program or a person. The verification code is usually used to prevent malicious programs such as Trojans from cracking a password, casting votes repeatedly, bumping in a forum, and so on, in order to prevent a certain hacker from making persistent login attempts by using a specific program to crack certain registered users violently or the like. The verification code is generally composed of lines and irregular characters, and is primarily intended to prevent a hacker from making a password into data and stealing the password. Currently, mainstream verification codes have the following forms:
1. A verification code is composed of only digits and letters, which may be all letters or all digits, and is a random string of a plurality of bits. This type of verification code is the most original, and its verification effect is almost zero in the current technical environment.
2. A verification code is an image verification code consisting of random digits+random uppercase letters+random interfering pixels+random positions+random length. The verification code is randomly generated, relatively secure, but difficult for verification and inconvenient for a user to input.
3. An advertisement verification code: a part of the content in an advertisement is input, which can bring additional revenues to a website and is also refreshing to the user.
4. A question verification code: a verification code is input mainly in a question-and-answer manner.
The above technologies have many disadvantages. First, every time after inputting a username and a password, the user has to switch to a keyboard to input characters. Especially, if the user needs to input characters on a touchscreen, the process is rather complicated, which brings poor user experience and is troublesome to the user. Secondly, a verification code usually includes stacked texts and is user-unrecognizable, which forces the user to keep refreshing the verification code image. Thirdly, a verification code is input to prevent attacks from malicious programs and keep a server system in secure state, but in practice, it mostly prevents the user from using the service pleasantly, causes troubles to the user, and brings no significant improvement to security.